Abstract: This study aimed to investigate the environmental risks of Total Mercury (THg) accumulation in Sentani Lake, Papua, Indonesia. THg was assessed around the Sentani Lake. Sampling survey for Water column, sediment, bivalve, pelagic and benthic fishes samples were collected in one time collection. Furthermore and potential environmental and health risks were determined using hazard quotient (HQ) and target hazard quotient (THQ) equation. Results revealed the concentration of Hg in water column, sediment, bivalve, pelagic and benthic fishes were ranged from 0.002 to 0.076 µg L-1, 115 to 184 µg kg-1 dw, 0.024 to 1.678 µg kg-1 ww, 0.017 to 1.265 µg kg-1ww and 0.139 to 1.845 µg kg-1ww, respectively. The elevated values of Mercury concentrations were observed in sediment and benthic fish (at the maximum concentrations of 1.678 µg kg-1dw and 1.845 µg kg-1ww), respectively. The magnitude of environmental Hazard Quotient for water and sediment showed that 0.001 – 0.038 and 0.66 – 1.06, respectively. In addition, the high values of target hazard quotient (THQ) for water column, bivalve, pelagic and benthic fishes were in the range of 0.004 to 0.252, 0.005 to 0.190 and 0.024 to 0.277, respectively. All those levels have not exceeded the limit standard or < 1 for potential health risks which mean safe for consumption. This study suggested that the magnitude of Hg concentration in Sentani Lake is generated primarily by the atmospheric fall down from some industries and amalgamation process where some people burn the gold ore. This area is surrounded by major number of Hg from industry and home scale industry directly emitted their waste to Sentani Lake. In case of health risks assessment by comparing with PTWIs and THQ, (based on the bivalve and fish consumption, for 70 years life span of 60 kg body weight), it indicated that people who consumed bivalve and fish from Sentani Lake were not at risk, however, they might be posed a risk due to the long and continual period of consumption.

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